Published on 30 April 2014
by Ricardo Catalinas Jiménez

I just wanted to share a simple script I use when I'm working late in my computer. Apparently there is evidence that blue light affects sleep and I've been testing it for some time and I can say that I feel the difference. After reducing my exposure to blue light before going to bed I feel more tired and more predisposed to sleep.

I don't like installing additional applications for this kind of purpose, thus I'm using this embarrassedly simple script to reduce the blue component and the brightness of all my Xorg displays:

#!/bin/sh

adjust_output() {
	for out in $(xrandr | sed -n 's/^\([^ ]*\).*\<connected\>.*/\1/p'); do
		xrandr --output $out --gamma $1 --brightness $2
	done
}

case $1 in
	off) adjust_output 1:1:1   1.0 ;;
	*)   adjust_output 1:1:0.5 0.7 ;;
esac